1. Field of the Invention
The present invention relates to a method and apparatus for monitoring the necessary energy and/or tonnage for a particular application of a mechanical press and for adjusting clutch torque to achieve this necessary energy and/or tonnage. Adjusting clutch torque to achieve the minimum necessary operating tonnage lessens possible press damage caused by a die wreck.
2. Description of the Related Art
Mechanical presses of the type performing stamping and drawing operations employ a conventional construction which includes a frame structure having a crown and a bed and which supports a slide in a manner enabling reciprocating movement toward and away from the bed. The slide is driven by a crankshaft. A connecting rod is operatively connected to the crankshaft and slide. The connecting rod is operative to transmit the rotational energy of the crankshaft into reciprocal movement of the slide. These press machines are widely used for a variety of workpiece operations and employ a large selection of die sets with the press machine varying considerably in size and available tonnage depending upon its intended use.
Conventional press machines employ a tooling apparatus in the form of a die assembly to shape a workpiece, such as in a stamping or drawing operation. The die assembly particularly includes a lower die attached to the bed or bolster and an upper die or punch attached to the slide. The upper and lower dies are installed in opposing spaced-apart relation to one another and cooperate during press machine operation to mutually engage the workpiece at respective sides thereof to thereby effect the desired forming activity.
Press operational problems occur when foreign material enters the die set. Large pieces of foreign material entering the die set can cause a die wreck in which the die set of the mechanical press can be significantly damaged. Additionally, contacting large pieces of foreign material or debris during press operation will create excessive vibration throughout the press.
Many mechanical presses employ a hydraulic overload protection device which serves to alleviate problems associated with foreign objects entering the die set. Such hydraulic overload protection devices are of limited utility as they commonly provide protection only with respect to foreign objects small in height. Larger foreign objects would exceed the capacity of the overload protection device and cause die or press damage.
What is needed in the art is a method and apparatus for preventing or lessening the effect of die destruction and associated problems which can occur when large foreign objects enter the die set.